Air Pump Cylinder

ABSTRACT

An air pump cylinder has a housing, a cover and an O-ring. The housing includes a connecting tube. The connecting tube has a plurality of projections extending therefrom. The cover is hermetically engaged with the connecting tube of the housing and includes a cap. The cap has an annular sidewall and a plurality of grooves. The grooves are formed in the annular sidewall and each groove has an axial portion and a locking portion. The projections of the connecting tube of the housing are disposed into the axial portions of the grooves and the cover is then rotated to make the projections engage the locking portions of grooves and to make the O-ring tightly clamped between the connecting tube of the housing and the cap of the cover. Therefore, the air pump cylinder can be easily assembled and manufactured without the use of bolts.

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to an air pump, and more particularly to an air pump cylinder that can be easily and quickly assembled and manufactured.

2. Description of the Prior Arts

An air pump is used to pump air and is driven by electricity or manual power. With reference to FIG. 7, a conventional air pump driven by electricity comprises an air pump cylinder 80 and an electric drive mechanism. The air pump cylinder 80 includes a housing 81, a cover 82, a plurality of bolts 83 and an O-ring 84. The housing 81 and the cover 82 are made of zinc alloy. The housing 81 has a plurality of threaded holes therethrough. The cover 82 has a plurality of through holes therethrough. The bolts 83 pass through the through holes of the cover 82 and are screwed into the threaded holes of the housing 81 to hermetically secure the cover 82 to the housing 81. The O-ring 84 is clamped between the cover 82 and the housing 81. A pipe has one end connected to the cover 82 and the other end connected to an inflatable article such as a tire tube. The electric drive mechanism includes a motor 91 and a gearing 92. In operation, the motor 91 drives a piston rod 90 to move in a reciprocating motion in the housing 81 of the air pump cylinder 80 via the gearing 92. The reciprocation of the piston rod 90 compresses air in the housing 81 and then the compressed air is ejected into the inflatable article for inflating the inflatable article.

However, hermetically securing the cover 82 to the housing 81 by means of bolts 83 requires a long processing time and thus reduces efficiency. In addition, forming the threaded holes through the zinc alloy housing 81 is troublesome and time-consuming.

To overcome the shortcomings, the present invention provides an air pump cylinder to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide an air pump cylinder that can be easily and quickly assembled and manufactured.

To achieve the foregoing objective, the air pump cylinder in accordance with the present invention comprises a housing, an O-ring and a cover. The housing includes a base tube and a connecting tube. The base tube has a front end and a piston chamber. The connecting tube is integrally formed on the front end of the base tube and has an outer surface, a valve chamber and a plurality of projections. The valve chamber communicates with the piston chamber of the base tube. The projections extend from the outer surface of the connecting tube. The O-ring is mounted around the connecting tube of the housing. The cover is hermetically engaged with the connecting tube of the housing and includes a cap. The cap has a closed front, an annular sidewall, a receiving chamber and a plurality of grooves. The annular sidewall has an inner surface. The receiving chamber receives the connecting tube of the housing and the O-ring. The grooves are formed in the inner surface of the annular sidewall, correspond to the projections of the connecting tube of the housing, and each groove has an axial portion and a locking portion. The locking portion extends from and communicates with a front end of the axial portion. The projections of the connecting tube of the housing are disposed into the axial portions of the grooves of the cap of the cover and the cover is then rotated to make the projections engage the locking portions of the grooves and to make the O-ring tightly clamped between the connecting tube of the housing and the cap of the cover. Therefore, the air pump cylinder can be easily and quickly assembled without the use of bolts. Besides, threaded holes through the housing are not required, thereby saving manufacturing time and cost.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially exploded perspective view of an air pump with an air pump cylinder in accordance with the present invention;

FIG. 2 is a perspective view of the air pump with the air pump cylinder in FIG. 1;

FIG. 3 is a top view in partial section of the air pump with the air pump cylinder in FIG. 1;

FIG. 4 is a partial perspective view of the air pump cylinder in FIG. 1;

FIGS. 5 and 6 are partial enlarged top views of the air pump with the air pump cylinder in FIG. 1 showing that the air pump is pumping air; and

FIG. 7 is a top view in partial section of a conventional air pump in accordance with the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 to 3, an air pump cylinder 1 in accordance with the present invention comprises a housing 10, an O-ring 20 and a cover 30.

The housing 10 is made of plastic or alloy, is integrally formed as one piece and includes a base tube 11, a connecting tube 12 and an interface wall 13. The base tube 11 has a front end, a rear end 112 and a piston chamber 111. The piston chamber 111 is defined in the base tube 11. A piston rod 60 is inserted in the piston chamber 111 from the rear end 112. The connecting tube 12 is formed on the front end of the base tube 11 and has an outer surface, a valve chamber 121, and a plurality of projections 124. The valve chamber 121 is defined in the connecting tube 12 for receiving a valve 40 that includes a body 41 and a spring 42. The projections 124 extend from the outer surface of the connecting tube 12. The interface wall 13 is formed between the base tube 11 and the connecting tube 12 and has a center, a hole 131 and an abutting surface 132. The hole 131 is formed through the center of the interface wall 13 and communicates with the piston chamber 111 of the base tube 11 and the valve chamber 121 of the connecting tube 12. The abutting surface 132 is formed around the hole 131. The body 41 of the valve 40 abuts the abutting surface 132.

The O-ring 20 is made of a resilient material such as rubber and is mounted around the connecting tube 12 of the housing 10.

The cover 30 is made of plastic or alloy, is integrally formed as one piece, is hermetically engaged with the connecting tube 12 of the housing 10 and includes a cap 31 and a joint 32. The cap 31 has a closed front, an open rear, an annular sidewall, a receiving chamber 311, a block 312 and a plurality of grooves 313. The closed front has an inner surface and an outer surface. The annular sidewall has an inner surface. The receiving chamber 311 is defined between the closed front and the annular sidewall of the cap 31 for receiving the connecting tube 12 of the housing 10 and the O-ring 20. The block 312 extends from the inner surface of the closed front. The spring 42 of the valve 40 is compressed between the block 312 and the body 41 of the valve 40. The grooves 313 are formed in the inner surface of the annular sidewall, correspond to the projections 124 of the connecting tube 12 of the housing 10 and each groove 313 has an axial portion and a locking portion 314. The locking portion 314 extends from and communicates with a front end of the axial portion. The projections 124 of the connecting tube 12 of the housing 10 are disposed into the axial portions of the grooves 313 and the cover 30 is then rotated to make the projections 124 engage the locking portions 314 of grooves 313 and to make the O-ring 20 tightly clamped between the connecting tube 12 of the housing 10 and the cap 31 of the cover 30. The O-ring 20 creates a seal between the housing 10 and the cover 30. The O-ring 20 provides a resilient force to the housing 10 and the cover 30 so that the housing 10 and the cover 30 are firmly connected to each other. Besides, the compressed spring 42 provides a restoring force to the housing 10 and the cover 30 to connect the housing 10 and the cover 30 as well.

The joint 32 is formed on the outer surface of the closed front of the cap 31 and has a passage 321. The passage 321 is defined in the joint 32 and extends through the block 312 of the cap 31 to communicate with the receiving chamber 311 of the cap 31. The joint 32 is connected to one end of a pipe and the other end of the pipe is connected to an inflatable article. Further, a pressure gauge connector 33 is mounted on the annular sidewall of the cap 31, is connected to a pressure gauge and has an interior communicating with the receiving chamber 311 of the cap 31.

In a preferred embodiment, the connecting tube 12 of the housing 10 has a cylindrical rear portion 123 and a cylindrical front portion 122. The rear portion 123 extends from a front surface of the interface wall 13 of the housing 10 and has a front surface, an outer surface and an outer diameter. The projections 124 extend from the outer surface of the rear portion 123. The front portion 122 has a cylindrical first step 126, a cylindrical second step 125 and an annular step surface 127. The first step 126 extends from the front surface of the rear portion 123 and has a front surface and an outer diameter. The outer diameter of the first step 126 is smaller than the outer diameter of the rear portion 123. The second step 125 extends from the front surface of the first step 126 and has an outer diameter. The outer diameter of the second step 125 is smaller than the outer diameter of the first step 126. The step surface 127 is formed between the first step 126 and the second step 125.

The receiving chamber 311 of the cap 31 of the cover 30 has a first tank 316, a second tank 315 and an annular step surface 317. The first tank 316 extends through the cap 31 from the open rear and has an inner diameter. The inner diameter of the first tank 316 corresponds to the outer diameter of the first step 126 of the front portion 122. The second tank 315 extends through the cap 31, communicates with the first tank 316 and has an inner diameter. The inner diameter of the second tank 315 corresponds to the outer diameter of the second step 125 of the front portion 122. The step surface 317 is formed between the first tank 316 and the second tank 315 and corresponds to the step surface 127 of the front portion 122. The O-ring 20 is mounted around the second step 125 of the front portion 122, is disposed in the first tank 316 of the receiving chamber 311 and is tightly clamped between the step surface 127 of the front portion 122 and the step surface 317 of the receiving chamber 311.

With reference to FIG. 4, the housing 10 has a recess 128 and the annular sidewall of the cap 31 of the cover 30 has a boss 318 engaging the recess 128 to ensure that the cover 30 does not rotate relative to the housing 10. Preferably, the recess 128 is formed in a periphery of the front surface of the interface wall 13 of the housing 10 and the boss 318 extends from a rear surface of the annular sidewall of the cap 31 of the cover 30.

The air pump cylinder 1 in accordance with the present invention can be easily and quickly assembled by rotating the cover 30 at a small angle relative to the housing 10 without the use of bolts. Besides, threaded holes through the housing 10 are not required, thereby saving manufacturing time and cost.

The air pump cylinder 1 in accordance with the present invention is applied to an air pump that comprises a drive mechanism. The drive mechanism may be manual or electric. The drive mechanism as shown is electric and includes a motor 50 and a gearing 51. In operation, the motor 50 drives the piston rod 60 to move in a reciprocating motion in the piston chamber 111 of the housing 10 via the gearing 51. With reference to FIG. 5, each time a piston 61 of the piston rod 60 is moved toward the valve 40, air is compressed by the piston 61. The compressed air pushes the body 41 against the restoring force of the spring 42 to open the hole 131 of the housing 10 and then ejects into the inflatable article through the passage 321 of the cover 30 for inflating the inflatable article. With reference to FIG. 6, each time the piston 61 of the piston rod 60 is moved away from the valve 40, a negative pressure in the piston chamber 111 is generated so that ambient air can flow into the piston chamber 111 through a gap between an outer surface of the piston 61 and an inner surface of the base tube 11. Thus, a pumping effect is achieved.

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. An air pump cylinder comprising: a housing including: a base tube having: a front end, and a piston chamber defined in the base tube; and a connecting tube integrally formed on the front end of the base tube and having: an outer surface; a valve chamber defined in the connecting tube and communicating with the piston chamber of the base tube; and a plurality of projections extending from the outer surface of the connecting tube; an O-ring made of a resilient material and mounted around the connecting tube of the housing; and a cover hermetically engaged with the connecting tube of the housing and including: a cap having: a closed front; an annular sidewall having an inner surface; a receiving chamber defined between the closed front and the annular sidewall of the cap for receiving the connecting tube of the housing and the O-ring; and a plurality of grooves formed in the inner surface of the annular sidewall, corresponding to the projections of the connecting tube of the housing and each groove having: an axial portion; and a locking portion extending from and communicating with a front end of the axial portion; and a joint integrally formed on the closed front of the cap and having a passage defined therein and communicating with the receiving chamber of the cap; and wherein the projections of the connecting tube of the housing are disposed into the axial portions of the grooves and the cover is then rotated to make the projections engage the locking portions of grooves and to make the O-ring tightly clamped between the connecting tube of the housing and the cap of the cover.
 2. The air pump cylinder as claimed in claim 1, wherein the connecting tube of the housing has a cylindrical rear portion extending from the front end of the base tube and having: a front surface; an outer surface from which the projections extend; and an outer diameter; and a cylindrical front portion having: a cylindrical first step extending from the front surface of the rear portion and having: a front surface; and an outer diameter being smaller than the outer diameter of the rear portion; a cylindrical second step extending from the front surface of the first step and having an outer diameter being smaller than the outer diameter of the first step; and an annular step surface formed between the first step and the second step; and the receiving chamber of the cap of the cover has a first tank extending through the cap from an open rear thereof and having an inner diameter corresponding to the outer diameter of the first step of the front portion; a second tank extending through the cap, communicating with the first tank and having an inner diameter corresponding to the outer diameter of the second step of the front portion; and an annular step surface formed between the first tank and the second tank and corresponding to the step surface of the front portion; and wherein the O-ring is mounted around the second step of the front portion, is disposed in the first tank of the receiving chamber and is tightly clamped between the step surface of the front portion and the step surface of the receiving chamber.
 3. The air pump cylinder as claimed in claim 1, wherein the housing includes an interface wall formed between the base tube and the connecting tube and having: a center; a hole formed through the center of the interface wall and communicating with the piston chamber of the base tube and the valve chamber of the connecting tube; and an abutting surface formed around the hole.
 4. The air pump cylinder as claimed in claim 2, wherein the housing includes an interface wall formed between the base tube and the connecting tube and having: a center; a hole formed through the center of the interface wall and communicating with the piston chamber of the base tube and the valve chamber of the connecting tube; and an abutting surface formed around the hole.
 5. The air pump cylinder as claimed in claim 4 further having a pressure gauge connector mounted on the annular sidewall of the cap of the cover and having an interior communicating with the receiving chamber of the cap.
 6. The air pump cylinder as claimed in claim 1, wherein the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess.
 7. The air pump cylinder as claimed in claim 2, wherein the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess.
 8. The air pump cylinder as claimed in claim 3, wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess.
 9. The air pump cylinder as claimed in claim 4, wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess.
 10. The air pump cylinder as claimed in claim 5, wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess.
 11. The air pump cylinder as claimed in claim 6, wherein the recess is formed in a periphery of a front surface of an interface wall of the housing; and the boss extends from a rear surface of the annular sidewall of the cap of the cover.
 12. The air pump cylinder as claimed in claim 7, wherein the recess is formed in a periphery of a front surface of an interface wall of the housing; and the boss extends from a rear surface of the annular sidewall of the cap of the cover.
 13. The air pump cylinder as claimed in claim 8, wherein the recess is formed in a periphery of a front surface of the interface wall of the housing; and the boss extends from a rear surface of the annular sidewall of the cap of the cover.
 14. The air pump cylinder as claimed in claim 9, wherein the recess is formed in a periphery of a front surface of the interface wall of the housing; and the boss extends from a rear surface of the annular sidewall of the cap of the cover.
 15. The air pump cylinder as claimed in claim 10, wherein the recess is formed in a periphery of a front surface of the interface wall of the housing; and the boss extends from a rear surface of the annular sidewall of the cap of the cover. 